Lectures 8,9+10- Skin Infections (Asynchronous) Flashcards
Bacterial skin infections
*erysipelas= acute inflammation of the dermis
*folliculitis= infection of the hair follicles
*impetigo= staph/strep superficial skin infection
*ecthyma= deeper variation of impetigo
*cellulitis= infection of lower skin layer causing inflammation
*necrotizing faciitis= severe skin infection
Acne
-occurs when sebum channels are blocked with shed cells
-allows anaerobic propinoibacterium acne to grow and digest sebum
-attracts neutrophils; enzymes cause lesions + pus pockets
Treatments;
*isotretinoin= prevents sebum formation
*tetracycline= antibiotics
*benzoyl peroxide= loosens clogged follicles
*visible blue light= kills p.acne
Impetigo
-skin infection; common in children
-staphylococcus/streptococcus
-spread via direct contact with lesions
-characterised by thick, yellow crystal on pus filled lesions; on face
Treatment= topical antibiotics
Erysipelas
-inflammation of the dermis
-commonly in elderly + immunocompromised
Fever, chills= systemic symptoms
-can spread rapidly
-painful
-caused by streptococcus pyogenes; group A beta=hemolytic
Treatment= oral/IV antibiotics= penicillins, clindamycin or erythromycin
Cellulitis
Skin= red, hot and painful
-deeper tissues
-inflammation is diffused and spreads along the tissues
-can exist alone with no pus
-caused by group A streptococci/staphylococcus aureus
-follows an innocuous injury/ wound
-oral/IV antibiotics
PVL positive s.aureus
Panton-valentine leukocidin= cytotoxin which destroys white blood cells= causes extensive tissue necrosis and severe infection
-toxin produced by some strains of S.aureus
-causes of cellulitis, abscesses, boils and carbuncles
-common in community MRSA strains
Doesn’t respond to standard staph treatment= may require de-colonisation
PVL= the 5 C’s
*close contact= contact sports/ skin-to-skin contact with an infected member
*contaminated items= gym equipment, towels/ razors
*crowding= military, prisons + boarding schools
*cleanliness
*cuts and grazes
MRSA
Slide 16
Staphylococcal scalded skin syndrome (SSSS)
-characterized by skin exfoliation
Fever, skin hypersensitivity + erythema= symptoms which leads to fluid filled blisters and skin separating
-mainly in infants + children
-immature immune systems + weak renal clearance
-treatable in children
*exfoliative toxins/epidermolytic toxins= serine proteases that cleave keratinocytes junctions -> disrupts cell-cell adhesion in the epidermis
^induces skin peeling
Necrotising fasciitis
-streptococcus Pyogenes
Rare infection of the deeper skin layers + subcutaneous tissues= spread quickly
*type I- polymicrobial infection
*type II- monomicrobial infection
-very painful, spreads rapidly, altered mental status, low bp, rapid surgery required to remove the dead tissue
-antibiotics help but don’t stop the spread
Fever, chills, sweats and weakness= symptoms
Myonecrosis (gas gangrene)
*clostridium perfingens infection= strict anaerobes + toxic former
-deep tissue infection
-local edema and pain; fever and tachycardia = pus formation, gas, foul smell
-incubation periods
*penicillin G/ chloramphenicol = surgical removal of infected muscle
Wound infections
Lower limb wounds; diabetic foot ulcers= common
-infection= prevents healing —> becomes permanently infected (can be difficult to treat)
RF=
- vascular disease, demeanour, malnutrition, diabetes, alcoholism, corticosteroids
Diabetic ulcers
Sores on feet= common in diabetic patients
Heel and big toe= common areas
-likely infection
Viral infections
Slides 2-4
Warts;
-common & most people are infected by papillomaviruses
-contact transmission; fomite
Treatment= removal
Chicken pox + shingles
CP;
-transmitted by the respiratory route
-causes pus-filled vesicles
-may remain latent in dorsal root ganglia
Shingles;
-reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin
Herpes simplex 1+2
-cold sores/fever blisters
*herpes gladiatorum = vesicles on skin)
*herpes whitlow= (vesicles on fingers)
*herpes encephalitis
HHV-1 = can remain latent in trigeminal nerve ganglia
HHV-2= can remain latent in sacral nerve ganglia
-acyclovir may lessen symptoms
Measles
-transmitted by respiratory route
-macular rash + koplik’s spots; prevented by vaccination
*subacute sclerosing panencephalitis= results from a measles viral infection acquired later in life
-always fatal
Rubella (German measles)
-rubella virus; macular rash and fever
-congenital rubella syndrome= causes severe fetal damage
-prevented by vaccination
Fungal infections + others
Fungal diseases; mycoses
*cutaneous mycoses= surface, ringworm, athletes foot and nail infections
-trichophyton= infects hair, skin + nails
-epidermophyton= infects skin + nails
-microsporum= infects hair + skin
Treatment= oral griseofulvin/ topical miconazole
*subcutaneous mycoses; deeper tissue, candida and sporotrichosis (rose gardeners disease- usually treated with *itraconazole/fluconazole)
-caused by injection of fungi into skin; injury + more common in warm humid countries
Ringworm
Transmitted by skin-skin contact
Ring-shaped, scaly itching patches on the skin
Treatment= topical antifungal drugs
Candidiasis
Result from suppression of competing bacteria by antibiotics
Occurs in skin; mucous membranes of genitourinary tract + mouth
Thrush= infection of mucous membranes of mouth
Topical treatment= miconazole/nystatin
Others
*Leishmaniasis; protozoan disease
-transmitted by sand flies from rodents + dogs
Common in Africa, Asia, Europe, Nor+ Sou America
Cutaneous from; skin ulcers on face, arms + legs
*Scabies; burrows in the skin to lay eggs
Treatment= topical insecticides
*Hookworm; parasitic larvae found in dog+cat faeces
-penetrate outer layers of skin
-lives and moves underneath the skin
-red,itching eruption= serpentine track + painful
Treatment= albendazole
